WASHINGTON — The U.S. House of Representatives voted again Thursday to allow the indefinite military detention of Americans, blocking an amendment that would have barred the possibility.

Congress wrote that authority into law in the National Defense Authorization Act two years ago, prompting outrage from civil libertarians on the left and right. President Barack Obama signed the measure, but insisted his administration would never use it.

Supporters of detention argue that the nation needs to be able to arrest and jail suspected terrorists without trial, including Americans on U.S. soil, for as long as there is a war on terror. Their argument won, and the measure was defeated by a vote of 200 to 226.

But opponents, among them the Rep. Adam Smith (D-Wash.), who offered the amendment to end that authority, argued that such detention is a stain on the Constitution that unnecessarily militarizes U.S. law enforcement.